Hydroxy-terminated polybutadiene is widely used as a binder for polyurethane-based solid propellants because of its low viscosity and good low-temperature properties. The main chain in the isocyanate cured hydroxyl-terminated polybutadiene is hydrocarbon. Binders with energetic groups on the chain are desirable for increased performance.
One of the most-used approaches to the development of energetic propellant binders is to apply epoxide polymerizations to form oligomers, which are then treated with di- or polyisocyanates to form the polymer backbone. Examples include GAP (glycidyl azide polymer) and PGN (polyglycidyl nitrate), R. L. Willer and R. S. Day, Proceedings of the APDA Joint International Symposium on the Compatibility of Plastics and Other Materials with Explosives, Propellants and Ingredients, American Defense Preparedness Association, October, 1989, 258, Poly(Glycidyl Nitrate) Revisited; R. L. Willer, A. G. Stern, D. McGrath, 1990 JANNAF Propulsion Meeting, CPIA Publication 550, 3, 223, Poly(Glycidyl Nitrate) and Poly(Glycidyl Nitrate) Propellants. Epoxide polymerization has been developed to the extent that functionality and molecular weight can be controlled readily. Energetic groups can be added before the polymerization step, as in the case of PGN, or after, as with GAP.
PGN has been synthesized by the preparation of glycidyl nitrate, followed by Lewis acid polymerization, Willer, et. al., U.S. Pat. No. 5,120,827. GAP could not be synthesized in this way because glycidyl azide could not be polymerized cleanly, so it was prepared by polymerization of epichlorohydrin, followed by the displacement of chlorine atoms on the polymer by azide ions, M. B. Frankel, et. al., GAP Polymer Demonstration, Report RI/RD80-240, AD-B057531L, Rocketdyne, January 1981; J. C. Gray, et. al., Energetic Ingredients for Gun Propellant, Report RI/RD81-109, AD-B057310L, Rocketdyne, January 1981.
Readily available alcohols with high nitro content, such as 2,2-dinitropropanol and 2,2,2-trinitroethanol would appear to be logical choices for reacting with epichlorohydrin to give glycidyl ethers. However, under the basic conditions that are normally used to form glycidyl ethers, these alcohols lose formaldehyde to give the resonance-stabilizedsalts of 1,1-dinitroalkanes.

The inability to attach dinitropropyl groups directly to the glycidyl moiety prompted Kim, et. al., to synthesize dinitropropyl glycidyl carbonate, Kim, et. al., U.S. Pat. No. 6,706,849, and dinitropropyl glycidyl formal, Kim, et. al., U.S. Pat. No. 7,427,687, Kim, et. al., U.S. Pat. No. 7,208,637, and the corresponding polymers. The extra connecting groups result in substantial dilution of the nitro content of the polymers.
